Aims:
As a consequence of global migration flows the risk of HPA alloimmunization may be increased for recipients of platelets from ethnically diverse donors. In this study, the frequencies of HPA in donors of different geographical origin were determined in a Northeastern Italy Transfusion Department.
Methods:
One hundred and ninety-nine apheresis platelet donors, including Europeans (n = 154) and North Africans (n = 29), were enrolled. DNA was extracted with a commercial kit (Bee-Robotic). Extensive HPA genotyping was performed with BloodChip ID HPA (Progenika-Grifols). Chi-squared test for Hardy-Weinberg equilibrium was used to compare frequencies.
Results:
The allele a was clearly predominant for HPA 1-11 in both European and North African donors. The allele b was absent for HPA 6-7-8-10-11 in Europeans and for HPA 4-6-7-8-9-10-11 in North Africans. For HPA-15, allele b was more frequent than allele a in North Africans. One case of HPA-4ab and one case of HPA-9abw were detected in Europeans. All HPA genotypes were consistent with Hardy-Weinberg equilibrium. Gene frequencies between both ethnic groups were similar excepting HPA-2 (p = 0.0342).
Conclusion:
In our population, there should not be clinically relevant increased risk of post-transfusion purpura or platelet transfusion refractoriness secondary to antibodies to HPAs for recipients of platelet concentrates from blood donors of European and North African ethnicity.

Acknowledgements
We acknowledge Dr. Alessandro Moro for revising the statistical analysis. Dr. Jordi Bozzo (Grifols) is acknowledged for expert review of the text and editorial assistance in the preparation of the manuscript.

Author Contributions
Donatella Londero – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Mauro Miani – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Cristina Rinaldi – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Vivianna Totis – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published
Vincenzo de Angelis – Substantial contributions to conception and design, Acquisition of data, Analysis and interpretation of data, Drafting the article, Revising it critically for important intellectual content, Final approval of the version to be published

Guarantor of Submission
The corresponding author is the guarantor of submission.